Treatment of material in a vacuum



4 1J Z. Z

Aug. 10 1926.

'uga 10 1926. 1,595,474

O. MINTON TREATMENT OF MATERIAL IN A VACUUM Original Filed March 4, 1920 5 Sheets-Sheet 2 15 2'? NYENTOR BYW ATTORNEY Aug. 10 1926.

O. MINTON TREATMENT OF MATERIAL IN A VACUUM ATTORNEY 5 Sheets-Sheet 5 w 9 l c 4,. I E o 6K v M C l! MH Tl 1 r 6 O Z m 3 0 w ,e u 5 F t C f 1 o O 2 .1 .l .n v A u o 6 0 I o o m15 H 9 O 3 e Us e 5 .mlao 5 A, 4 @rf O 5 5 Patented Au'g. l0, 192.6.

UNITED STATES OGDEN MINTON,. OF GREENWICH, CONNECTICUT.

TREATMENT 0F MATERIAL IN A VACUUM.

Application led March-4, 192i), Serial No. 363,850. Renewed February 17, 1926.

The present inventionrelates .to an apparatus and method for the drying of paper and other" sheet material and immediately coating, or coloring, or sizing or impregnating it while still in the vacuum chamber.

My improved method consists in passing the sheet material which is to be dried into a vacuum chamber through a liquid sealing medium which has no afiinity for the material, subjecting it to heat to drive off its contained moisture, immediately coating or coloring, or sizing or impregnating the sheet material while in the vacuum chamber, and then passing the sheet material out of the chamber through a seal.

This method may be practiced by the use of various forms of apparatus, some of which are herein disclosed. In any form, however, it is essential that the apparatus be provided with a closed chamber in which a partial vacuum may be maintained. In order that the material to be dried and treated may be continuously passed through the vacuum chamber, the latter is provided with openings closed to the admission of air by a liquid sealing medium which has no afiinity for t-he material. The liquid seal effectively closes the entrance and exit passages against the admission of air to the chamber, but permits the passage of the material into and out of the chamber. The

heating elements within the vacuum chamber, for drying the material, the shape form, dimensions and location of the liqui seal containers, and the means for passing the sheet material through the chamber, may all vary. I have shown herein a number of varieties which I contemplate using. My invention further relates to obtaining a better and more uniform product than any now known on the market. My invention further relates to the method of coating or impregnating sheet material which insures that there will be no blemishes, uneven surfaces, blisters or minute raised portions due to the air which may be held or occluded within the sheet'material, which in the present practice of coating as for example with a water-proof compound, leads, to rejections or discards due to these 11n-- perfections with the consequent waste 'of material and labor.

My invention further relates to the treatment 0f paper and drying it ina vacuum chamber, and coating or impregnating or coloring it therein without breaking the vacuum. My invention further relates to performing these steps continuously on a contmuous web of paper. This web of paper may be fed direct from the Wet end of arpaper machine, or the web may be first Wound into a roll or reel as may be found convenient or expedient.

My invention further relates to manufacturing lpaper wherein the fibers are not.

weakened and the size in the paper is not injured or damaged due to drying' at high temperatures.

My invention further relates to manufacturing colored paper and drying it without substantially impairing the coloring matter and mordants used in the paper. Among other advantages this insures that the pal per will have bright colors, which will be substantially uniform in different runs of paper, permitting matching of colored paper without any appreciable difference in tone or color.

My invention further relates to rapidly and expeditiously coating or impregnating sheet material in a continuous web or sheet.

My invention further relates to sizing pa# per in a vacuum chamber at such low temperatures as not to injure the fibers of the paper oij the size. My invention further relates to withdrawing the occluded air from the paper and immediately drying and then filling the interstices normally filled with the occluded air with thel size. My invention further relates to carrying out this method continuously with a continuous web of paper which passes into and out of the vacuum chamber without partly diagrammatic, illustrate several, but

not the only, forms of my apparatus, by the use of which my improved method may be practiced.

In the accompanying drawings the same reference numerals refer to similar parts in the several figures.

Fig. 1 is a vertical diagrammatic section through one form of apparatus which may be used to carry out my improved process.

Fig-2 is a diagrammatic vertical section of a modified form in which the web of sheet material is passed through a heated bath to dry the same;

Fig. 3 is a vertical diagrammatic section of a modified form of apparatus in which a combination of heated drums and a heated bathv are used to dry and finish the sheet material;

Fig. 4 is a vertical diagrammatic section of another modification in which different sized drums are used with a heated 1i uid bath to vary the finish given to the s eet material;

Fig. 5 is a vertical diagrammatic section of still another modification in which the web of sheet material is passed in folds or loops through the vacuum chamber adjacent to but not in contact with fixed heating surfaces; and

Fig. 6 is a vertical diagrammatic section of still another modification in which the web of sheet material is fed through the vacuum chamber, and in its passage through said chamber subjected to convected heat, preferably a glowing member of an electric heater.

In describing` my invention I will .describe it as applied to sheet material in the form of paper though it is to be distinctly understood that textile fabrics may also be treated by my process and that my broader claims covers all forms of sheet materials.

In the ordinary drying of a web of paperl such high heat is used as to injuriously affect the fibers of the paper; and in case the paper is colored it will materially affect the coloring matter and mordants used. Drying paper in the high temperatures used in ordinary practice often affects the size so that the resulting paper varies in quality, is not uniform and is not a perfect product.

In coating or impregnating fabrics it is found in practice that the coated fabric will frequently have blemishes due to large or small blisters and blow holes, these often being about the size of a pin-head or pinpoint. This is caused by the air which is held or occluded being collected, more or less, in small pockets under the coating or impregnating material, or in some cases causing minute blow holes. In waterproof fabrics this results in large quantities of the material being rejected with the consequent loss to'the manufacturer.

By my invention I insure that substantially all the occluded air is withdrawn from the sheet materialwhich will permit the coating or impregnating material, whatever it may be, to thoroughly fill these minute inferstices or pockets normally occupied by occluded air, forming thereby a-better and more uniform product and one devoid of blisters, blow holes or such blemishes.

The web 1 of paper may be fed direct from the wet end o a paper machine, the vacuum chamber 2 being properly positioned adjacent to such paper machine. fOr, the

web 1 may be fed, from a roll or reel 3 p of wet or damp paper over the guide roller 4 and into the liquid seal 5. This seal may be of any suitable medium' which has no aiinity for or deleterious affect upon the sheet material treated. I preferably use a liquid seal of mercury, though it is to be distinctly understood, that any amalgam, alloy, or any other suitable liquid sealing medium may be employed which has the characteristics above specified. The web 1 is led down through this liquid seal under the roller 6 and then up into the vacuum chamber 2 in contact with the ide roller 7 and over one or more rotating heating drying drums 8 and 9. While I have shown two such drying drums, it is to be understood that one, or a greater number, than two, may be used if desired or expedient. To insure that the web 1 willncontact with as much of the periphery of the drying drums 8 and 9, as possible, I pass it down and under the guide rollers 10, 10.

The web is thoroughly dried in this manner while in the vacuum chamber. Substantially all its occluded air is also withdrawn and passes off with the steam and other vapor through the pipes 11, 11 to any suitable form of condenser or vacuum apparatus (not shown). While still in the vacuum chamber 2 and while dry I immediately subject the web 1, whether it be aper or textile material, to some suitablre coating oi' impregnating or coloring material in the chamber 12 in the form of a bath 13. This coating or impregnating or coloring material may be of any suitable material with which it is desired to coat or impregnate or color the web 1. For example it may be size, wax, tar or in fact any coating or waterproofing or impregnating or coloring material. Preferably, though not necessarily, I mount steam pipes 14, 14 in the bath 13 to heat it if this is desirable.

The web 1 passing into said coating or impregnating bath 13 dry, and with its interstices devoid of practically all occluded air will immediately become coated or'impregnated with portions of said bath as it passes under the submerging roller 15 and out between the squeeze rollers 16, 16, which remove all the surplus coating or impregnating material. The amount of the coating or impregnating material taken up by the web 1 will depend somewhat upon the speed with which the web is fed through the vacuum chamber, but it is to be understood that my machine is a high speed machine. The Web .will then pass over the guide rollers 17, 17 and down into the second liquid seal 5 under the roller 17. This liquid seal 5 is preferably of the same material as the first liquid seal 5, though'of course it need not necessarily be, but it must not have any afiinit Ifor or deleterious action upon the coate or impregnated web 1. The web is then fed over the guide roller 18 and is preferably rolled in the roll or reel 19, though it may be cut or stacked or further treated, as may be found convenient or expedient.

By my process the size or coloring matter and mordants, if any be used, will not be injuriously affected. The temperature of the rolls or drums may vary Within quite wide limits. The drums may be heated by exhaust steam' or hot Water or heated in any other suitable manner.

The vacuum chamber 2 is provided with windows, such for example as 20 and also with suitable man-holes and means to replenish the supply of the coating or .impregnating bath 13 (not shown). The liquid of this bath may be Withdrawn from the chamber 12 by operating the cock 21, preparatory to changing the bath or-cleaning out said chamber. If the coating or impregnating material includes valuable,- volatile liquids, which may be drawn off by the vacuum and which it may be desirable to use over' again, this may be done in any Well known manner. The vacuum in the chamber 2 not only removes the occluded air from the web 1, but it also removes the occluded air from the bath 13, so that a smoother and finer roduct is obtained Without any blemishes, blisters, or defects due to small portions of air being held under any of the coating; or in seeking to escape therefrom, causing pin-holes to appear on the surface. In passing the Web 1 over the revolving drying cylinders or drums 8 and 9 the sheet material, particularly if it is paper, is iven a smooth and fiat surface.

Different egrees of finish and smoothness may be imparted to the Webl, particularly if it is of paper, b drying it in a different manner While in the vacuum chamber and prior to coating or impregnating it.

I have shown for example a modification of my'invention in Fig. 2, in which the web 1 may be fed either from the wet end of a paper machine, or from the roll or reel 3 into the vacuum chamber 22 through the liquid seal 5. Unlike the apparatus shoyvn in Fig. l, the web 1 is dried in the vacuum chamber 2 by assing through a liquid heating bath 23 ci) a medium which has no affinity for or deleterious affect upon it. This liquid bath may be, and preferably is, heated mercury, though it may be any suitable amalgam. an alloy or any other suitable medium Which has the characteristics above specified. This bath may be heated in any suitable manner such as by the steam pipes 24, 24. The web passing over the guide rollers 25, 25 and under the submerging rollers 26, 26 will be thoroughly dried, preparatory to being coated or impregnated with the liquid 13, after which it will pass through the squeeze rollers 16, 16 and over the guide rollers 17, 17 and under the submerging roller 27 in the second liquid seal5.

In some cases it may be desirable to give the coated or impregnated web 1 a finish and smoothness different from what it is given in the apparatus shown in Figs. 1 and 2. I may for example pass the Web 1, Fig. 3, into a vacuum chamber 28, and then through a liquid heating bath 23 having the.

characteristics above mentioned. In passing theV web 1 through this heating bath 23. I employ drums 29, 29 which may be heated or not and which are partially submerged in the bath.v These drums may be rotated if desired in any suitable manner.

The web 1 passing through the vacuum chamber 28 in contact With these drums 29, 29 and also over the guide roller 30, 30 is thoroughly dried and then passes over the guide roller 31 and into the coating or impregnating bath 13, and out through the squeeze rollers 16, 16 and the second liquid seal 5 in the manner previously described in connection with the other forms. The liquid bath 23 may be heated in any suitable manner such as by passing steam', hot water, or products of combustion through the chamber 32.

The finish and smoothness of the Web 1 may be still further varied by changing the size of the rollers 29, 29. These changes may be made Within wide limits. Simply for purpose of illustration I have shown in Fig. 4, a vacuum chamber 33 in which the same heating bath 23 is employed but instead of the drums 29, 29 I employ drums 34, 34 which are considerably smaller in cross section. In this modification `the web 1, particularly if it is of paper, Will not have quite so fiat and smooth a finish as it would have by employing the apparatus of Figs. 1 and 3, but it will have a smoother and flatter finish than that given by the apparatus of Fig. 2. While these different forms arev shown it is of course to be understood that they are simply illustrative and that vmy invention is not to be confined t0 them.

The forms shown in Figs. 2-4 are the subject of my divisional application Serial No. 545,216.

It is desirable in finishing some Webs of sheet material, particularly paper, to pass them adjacent to, but not in contact with, the heating element. I have shown in Fig.

l5, a' vacuum chamber 35, provided with fixed heating elements 36, 36. These 'elements are preferably heated with steam or hot Water. The wet or damp web 1 is fed through the vacuum chamber 35 in folds or loops 37, 37 over the lguide rollers 38, 38 and under the uide rollers 39,' 39. Between one or more o these folds or loops, preferably between each one of them, is mounted one of the fixed radiators 36, 36 so'that'as the web is fed through the vacuum chamber 35, these folds or loop's are heated by the radiators 36, 36. In this form of my invention, the web 1, particularly ifit is of paper,` is permitted to dry with little or no tension upon it, so that its constituent fibers can dry or shrink at random, making the slieets substantially as strong lengthwise as it" is crosswise of the sheet.

The web is then coated or impregnated while still subjected to the vacuum in the manner previousl described at length in connection with Vthe other forms of my invention.

In some cases I may use a vacuum chamber 40 in which the web 1' is fed through in folds or loops and in its passage is subjected to radiant heat, preferably the glowing member of an electric heater l1. These electric heaters are preferably placed between one or more of the folds or'loops so that the Web will be thoroughly dried. In this form of my invention, also, the web is dried in the vacuum chamber under little or no tension, so that its`strength lengthwise is substantially as strong as crosswise of the sheet.

The web is then coated or impregnated in the manner previously described in connection with the other forms of my invention.

The forms shown in Figs. 5 and 6 are the subject of my divisional application Ser. No. 545,217.

The thermal `efficiency of my vacuum `method is very much. greater than that of the atmospheric cylinder drying heretofore in universal use for drying aper. Theoretically, it requires about 5,28? pounds of steam to dry one ton of paper at atmospheric pressure, but to compensate for convection and conducting losses, and those due to leaks in the piping system, and other inefficiencies, it has been shown in practice that about 10,600 pounds are required.

Some of the modern open air paper dryers are equipped with a blower system by which air, either heated or not, is blown through the dryer section which is open to the atmosphere. This will lower the temperature at which the water is evaporated from the paper in such open air dryers much below 212o F., and may, in some cases, reduce the temperature of evaporation as low as 180 F. or lower.

In my method. using a vacuum of about 28, the convection, conduction and piping losses are exceedingly small and the total steam required to dry a ton of paper by my method is approximately 5,200 pounds.

It is an established fact that paper dried at.low temperatures is much stronger than when it is dried at the high temperatures used in paper machine atmospheric drying. Paper dried in a vacuum of 28, or at a temperature of about 100o F., as in my method, is very much stronger than paper dried at atmospheric pressure, when the steam in the driers is at 228 F. When paper is dried by my method, therefore, a cheaper furnish can be used and still produce a coated or sized paper equal in strength to atmospheric dried paper, in

which a higher grade furnish is used. In making newsprint paper, I am able to dispense with a considerable portion of the more expensive sulphite pulp, as this can be replaced with the cheaper ground wood pulp. By my method I also reduce the number of breaks in the web as it passes over the cylinder.

Furthermore, in my method there is a great saving of heat (or steam) because the process is carried on in a vacuum chamber which acts on the principle of a thermos bottle, and the steam and vapors driven out of the wet paper are caught in the closed vacuum chamber, and conducted away to the condenser. The operating room is free from steam, humidity and heat,'and-fans, and eX- hausters are dispensed with. In the use of mymethod the apparatus is at all times operating under deiinite humidity, the control of the drying can be closely standardized, and the moisture content in the paper carefully regulated.

Having pointed out the many advantages of my method and apparatus over those heretofore used, it will be apparent that the use of my invention results in great economy in the initial cost of apparatus and in large savings in cost of operation, maintenance and repairs.

Having thus described this invention in connection with illustrative embodiments thereof,- to the details of which I do not desire to be limited, what is claimed as new and what is desired to secure by Letters Patent isset forth in the appended claim.

What I claim is 'Ihe method of treating a wet web of paper consisting in continuously feeding it into a vacuum chamber without breaking the vacuum, continuously drying the web and at the same time pulling the fibers of the web more or less in the direction of the travel of the web, so as to more or less change their original matted or interlocked position formed-on the wire of the paper machine, then while still in the vacuum chamber continuously coating or impregnating the web, and continuously withdrawing the' coated or impregnated web from the vacuum chamber without breaking the vacuum.

OGDEN MINTON. 

